1. Field of the invention
Methods and apparatuses consistent with the present invention relate to transmitting an event in a web-based system, and more particularly, to an apparatus and method which can transmit an event having occurred in a controlled device to a control device without loss or delay in a web-based system.
2. Description of the Prior Art
According to the development of web technologies, the web is now utilized in various fields relating to web-based systems such as a home network for controlling home appliances including Audio Video (AV) appliances, beyond application to simple display of markup language documents such as Hyper Text Markup Language (HTML) documents.
For example, a current home network using the web may have a construction in which a digital television is equipped with a web browser so that a user of the digital television can control another device connected to the digital television, for example, a DVD player, by operating the web browser through a remote control.
In other words, in order to control various devices (hereinafter, referred to as “controlled devices”) included in a home network, a device (hereinafter, referred to as “control device”) capable of displaying a user interface, such as a digital television or a Personal Digital Assistant (PDA), is equipped with a web browser, so as to connect to a web server mounted in each of the controlled devices in order to control the controlled devices.
The control device provides a user interface for a predetermined controlled device, and a user can control the predetermined controlled device by using the user interface provided to the user. The control device may be equipped with user interfaces for controlling all controlled devices currently connected to the control device through the home network. However, the control device is not equipped with a user interface for a controlled device that is newly added to the home network, and it is thus necessary to download the user interface for the newly added controlled device in order to provide the new user interface to the user, which may be quite cumbersome.
Recently, even when a control device is not equipped with a user interface for a predetermined controlled device, the control device receives a user interface from a corresponding controlled device and provides the user interface to a user. Therefore, a user can control a corresponding controlled device even through a control device which is not equipped with a user interface for the corresponding controlled device.
Specifically, the control device connects with the web server of the controlled device through the web server of the control device and requests a user interface for control by a user to the controlled device through a Hyper Text Transfer Protocol (HTTP). In response to the request from the control device, the controlled device transmits the user interface to the control device through the HTTP. Then, the control device updates a currently displayed user interface to display the features of the user interface received from the controlled device.
Schemes for transmitting a user interface between a control device and a controlled device include an XMLHTTPRequest scheme, which is widely used in web server applications, such as Apache and IIS, and web browser applications, such as Internet Explore, Mozilla, Safari, etc.
The XMLHTTPRequest scheme is a scheme for transmission of a user interface,which is used in a single connection between a web browser and a web server. The XMLHTTPRequest scheme is effective in a system such as the Internet, in which events requested by the web browser do not frequently occur. However, when the event occurs, the XMLHTTPRequest scheme causes event delay or loss to occur and instant update of the user interface is necessary. Therefore, there has been a necessity for a scheme which can efficiently transmit an event without delay or loss even when events frequently occur.
Korean Laid-Open Patent No. 2005-0079480 discloses a home network service providing UPnP based RG system, which includes a central server (HNSN) connected to a mobile network to control devices and transfer control states of the devices, and a home gateway (RG) connected to multiple devices and to the central server. However, in the disclosed system, a user outside of a home network can remotely control all devices within the home network by using a browser. However, the Korean Laid-Open Patent fails to disclose a scheme for efficiently transmitting an event that occurred in a controlled device of a web-based system without delay or loss.